Screw Pump Varying Pitch Rotor Heat Dissipation
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Solution Overview
Problem
Screw pumps face issues with temperature disparity between rotors and stators due to heat generation from gas compression, leading to potential seizing, and existing cooling systems are costly and complex.
Innovation Solution
The design incorporates externally threaded, tapered rotors with increasing pitch towards the outlet, varying axial cross-sections, and conjugate forms to enhance heat transfer and sealing, eliminating the need for coolant flow by increasing the surface area for heat dissipation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a coolant system is added to cool the rotors, then the temperature disparity between rotors and stator is reduced, but the device complexity and cost increase
Solution Approach 1:
The rotor design enables self-cooling through its own geometry. The varying pitch threads create expansion spaces that allow heat to dissipate naturally during the pumping cycle, eliminating the need for external coolant systems while maintaining effective temperature control
Solution Approach 2:
The pitch of the threads is varied along the length of the rotor, creating different expansion spaces at different locations. This parameter change optimizes heat dissipation at critical high-temperature zones without requiring additional cooling components
2Productivity
If close tolerances are used between rotor threads and stator, then pumping efficiency is improved, but heat generation increases leading to rotor seizing
Solution Approach 1:
The rotor threads have non-uniform pitch along their length, creating local variations in compression and expansion zones. This allows efficient pumping in compression zones while creating heat-dissipating expansion spaces in high-temperature zones, addressing both efficiency and heat management locally
3Ease of manufacture
If constant pitch threads are used, then manufacturing is simplified, but pumping capacity at atmospheric pressures is reduced
Solution Approach 1:
The thread pitch is varied along the rotor length to optimize pumping capacity at different stages of compression. This parameter change improves atmospheric pressure pumping performance while maintaining manufacturability through standardized threading processes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves pumping capacity at atmospheric pressures with low power requirements, effectively managing heat and preventing rotor-stator seizing without additional cooling systems, thus reducing operational costs.
Implementation Method 1
the stator housing first and second externally threaded rotors mounted on respective shafts and adapted for counter-rotation within the stator to compress fluid passing from the fluid inlet to the fluid outlet
Implementation Method 2
the axial cross-section of the rotors varying from the fluid inlet towards the fluid outlet, and the threads having a pitch that increases towards the fluid outlet
Data Source
AI summary
A screw pump includes a stator having a fluid inlet and a fluid outlet, the stator housing first and second externally threaded, tapered rotors mounted on respective shafts and adapted for counter-rotation within the stator to compress fluid passing from the fluid inlet to the fluid outlet, wherein the threads have a pitch that increases towards the fluid outlet.